Ask the Diet Doctor: Alcohol and Immunity

A:Your immune system works to protect your body via two primary mechanisms, both of which can be affected by alcohol. The first mechanism is an immediate response, which uses an inflammatory approach to essentially "nuke" unwanted intruders. When your body senses a foreign bacteria or pathogen, it mobilizes immune cells called macrophages out of the bloodstream and into the part of your body that is being invaded that essentially "eat" the bad bacteria. Alcohol inhibits the macrophages’ ability to do this, and it also reduces your body's ability to produce inflammatory compounds that stun invading bad bacteria before the macrophages can break them down.

The other way the immune system works to protect your body in the long term is to identify and develop immunity to a particular pathogen. While researchers don’t entirely know why, alcohol reduces the number of T cells in your body, which are responsible for this protection, along with B cells. This leads to a reduced response toward infections. Alcohol also impairs the function and sometimes growth of B cells, the cells responsible for making antibodies against toxic substances like bacteria.

Alcohol can also impact our immune system in a more indirect fashion by disrupting circadian rhythms. The interplay between our 24-hour sleep/wake cycle and biological processes known as circadian rhythms is a fascinating aspect of human biology. Hormones, immune function, and even blood sugar control are all influenced by circadian rhythms. Asynchrony with circadian rhythms can cause annoying yet minor problems like jet lag, but it can also increase the risk of more serious problems like cardiovascular disease and diabetes. Alcohol’s ability to disrupt your sleep/wake cycles (by causing you to wake up more often throughout the night and reduce your quality of sleep) can be the tipping point of a physiological cascade that creates disruption in our circadian rhythms, leading to impaired immune function.

The takeaway? You can drink and maintain a healthy immune system, but the key is moderation. Heavy drinking—defined as more than eight drinks per week for women (more than 15 for men) or more than four to five drinks within a two-hour time span—can have detrimental effects on your immune defesnses and overall health. But while too much alcohol can increase your risk of dying at a younger age, completely abstaining from alcohol leads to the same fate. Plus, having a couple drinks per week is also one of the best ways to increase your HDL (good) cholesterol, so there's no reason to avoid it altogether.